Info file gdb, produced by texinfo-format-buffer   -*-Text-*-
from file gdb.texinfo

This file documents the GNU debugger GDB.

Copyright (C) 1987 Richard M. Stallman.

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided also that the
sections entitled "Distribution" and "GDB General Public License" are
included exactly as in the original, and provided that the entire resulting
derived work is distributed under the terms of a permission notice
identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions,
except that the sections entitled "Distribution" and "GDB General Public
License" may be included in a translation approved by the author instead
of in the original English.



File: gdb  Node: Top, Up: (DIR), Next: Commands

Summary of GDB
**************

The purpose of a debugger such as GDB is to allow you to execute another
program while examining what is going on inside it.  We call the other
program "your program" or "the program being debugged".

GDB can do four kinds of things (plus other things in support of these):

  1. Start the program, specifying anything that might affect its behavior.
     
  2. Make the program stop on specified conditions.
     
  3. Examine what has happened, when the program has stopped, so that you
     can see bugs happen.
     
  4. Change things in the program, so you can correct the effects of one bug
     and go on to learn about another without having to recompile first.

* Menu:

* License::    The GDB General Public License gives you permission
	       to redistribute GDB on certain terms; and also
	       explains that there is no warranty.
* Input::      GDB command syntax and input conventions.
* Files::      Specifying files for GDB to operate on.
* Switches::   GDB arguments and switches.
* running::    Running your program under GDB.
* Stopping::   Making your program stop.  Why it may stop.  What to do then.
* Stack::      Examining your program's stack.
* Source::     Examining your program's source files.
* Data::       Examining data in your program.
* Symbols::    Examining the debugger's symbol table.
* Altering::   Altering things in your program.
* Sequences::  Canned command sequences for repeated use.
* Commands::   Index of GDB commands.
* Concepts::   Index of GDB concepts.


File: gdb  Node: License, Prev: Top, Up: Top, Next: Input

GDB General Public License
**************************
                         (Clarified 20 March 1987)

  The license agreements of most software companies keep you at the mercy
of those companies.  By contrast, our general public license is intended to
give everyone the right to share GDB.  To make sure that you get the rights
we want you to have, we need to make restrictions that forbid anyone to
deny you these rights or to ask you to surrender the rights.  Hence this
license agreement.

  Specifically, we want to make sure that you have the right to give away
copies of GDB, that you receive source code or else can get it if you want
it, that you can change GDB or use pieces of it in new free programs, and
that you know you can do these things.

  To make sure that everyone has such rights, we have to forbid you to
deprive anyone else of these rights.  For example, if you distribute copies
of GDB, you must give the recipients all the rights that you have.  You
must make sure that they, too, receive or can get the source code.  And you
must tell them their rights.

  Also, for our own protection, we must make certain that everyone finds
out that there is no warranty for GDB.  If GDB is modified by someone else
and passed on, we want its recipients to know that what they have is not
what we distributed, so that any problems introduced by others will not
reflect on our reputation.

  Therefore we (Richard Stallman and the Free Software Foundation,
Inc.) make the following terms which say what you must do to be
allowed to distribute or change GDB.


Copying Policies
================

  1. You may copy and distribute verbatim copies of GDB source code as you
     receive it, in any medium, provided that you conspicuously and
     appropriately publish on each file a valid copyright notice "Copyright
     (C) 1986 Free Software Foundation, Inc." (or with the year
     updated if that is appropriate); keep intact the notices on all files that
     refer to this License Agreement and to the absence of any warranty; and
     give any other recipients of the GDB program a copy of this License
     Agreement along with the program.  You may charge a distribution fee
     for the physical act of transferring a copy.
     
  2. You may modify your copy or copies of GDB source code or any portion
     of it, and copy and distribute such modifications under the terms of
     Paragraph 1 above, provided that you also do the following:
     
        * cause the modified files to carry prominent notices stating who
          last changed such files and the date of any change; and
          
        * cause the whole of any work that you distribute or publish, that
          in whole or in part contains or is a derivative of GDB or any
          part thereof, to be licensed at no charge to all third
          parties on terms identical to those contained in this License
          Agreement (except that you may choose to grant more extensive
          warranty protection to third parties, at your option).
          
        * if the modified program serves as a debugger, cause it when started running
          in the simplest and usual way, to print an announcement including a valid
          copyright notice "Copyright (C) 1986 Free Software Foundation,
          Inc." (or with the year updated if appropriate), saying that there is no
          warranty (or else, saying that you provide a warranty) and that users may
          redistribute the program under these conditions, and telling the user how
          to view a copy of this License Agreement.
          
        * You may charge a distribution fee for the physical act of
          transferring a copy, and you may at your option offer warranty
          protection in exchange for a fee.
     
  3. You may copy and distribute GDB or any portion of it in compiled,
     executable or object code form under the terms of Paragraphs 1 and 2
     above provided that you do the following:
     
        * cause each such copy of GDB to be accompanied by the
          corresponding machine-readable source code; or
          
        * cause each such copy of GDB to be accompanied by a written offer,
          with no time limit, to give any third party free (except for a
          nominal shipping charge) machine readable copy of the
          corresponding source code; or
          
        * in the case of a recipient of GDB in compiled, executable or
          object code form (without the corresponding source code) you
          shall cause copies you distribute to be accompanied by a copy of
          the written offer of source code which you received along with
          the copy of GDB.
     
  4. You may not copy, sublicense, distribute or transfer GDB except as
     expressly provided under this License Agreement.  Any attempt
     otherwise to copy, sublicense, distribute or transfer GDB is void and
     your rights to use GDB under this License agreement shall be
     automatically terminated.  However, parties who have received computer
     software programs from you with this License Agreement will not have
     their licenses terminated so long as such parties remain in full
     compliance.
     
  5. If you wish to incorporate parts of GNU Emacs into other free programs
     whose distribution conditions are different, write to the Free Software
     Foundation.  We have not yet worked out a simple rule that can be stated
     here, but we will often permit this.  We will be guided by the two goals of
     preserving the free status of all derivatives our free software and of
     promoting the sharing and reuse of software.


NO WARRANTY
===========

  BECAUSE GDB IS LICENSED FREE OF CHARGE, WE PROVIDE ABSOLUTELY
NO WARRANTY, TO THE EXTENT PERMITTED BY APPLICABLE STATE LAW.  EXCEPT
WHEN OTHERWISE STATED IN WRITING, THE FREE SOFTWARE FOUNDATION, INC,
RICHARD M. STALLMAN AND/OR OTHER PARTIES PROVIDE GDB "AS IS"
WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING,
BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY
AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE GDB
PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY
SERVICING, REPAIR OR CORRECTION.

 IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW WILL FREE SOFTWARE
FOUNDATION, INC., RICHARD M. STALLMAN, AND/OR ANY OTHER PARTY WHO MAY
MODIFY AND REDISTRIBUTE GDB AS PERMITTED ABOVE, BE LIABLE TO YOU
FOR DAMAGES, INCLUDING ANY LOST PROFITS, LOST MONIES, OR OTHER
SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR
INABILITY TO USE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA
BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY THIRD PARTIES OR A
FAILURE OF THE PROGRAM TO OPERATE WITH PROGRAMS NOT DISTRIBUTED BY
FREE SOFTWARE FOUNDATION, INC.) THE PROGRAM, EVEN IF YOU HAVE BEEN
ADVISED OF THE POSSIBILITY OF SUCH DAMAGES, OR FOR ANY CLAIM BY ANY
OTHER PARTY.


File: gdb  Node: Input, Prev: License, Up: Top, Next: Files

GDB Input Conventions
*********************

GDB is invoked with the shell command `gdb'.  Once started, it reads
commands from the terminal until you tell it to exit.

A GDB command is a single line of input.  There is no limit on how long
it can be.  It starts with a command name, which is followed by arguments
whose meaning depends on the command name.  Some command names do not
allow arguments.

GDB command names may always be abbreviated if the abbreviation is
unambiguous.  Sometimes even ambiguous abbreviations are allowed; for
example, `s' is specially defined as equivalent to `step'
even though there are other commands whose names start with `s'.
Possible command abbreviations are often stated in the documentation
of the individual commands.

A blank line as input to GDB means to repeat the previous command verbatim.
Certain commands do not allow themselves to be repeated this way; these are
commands for which unintentional repetition might cause trouble and which
you are unlikely to want to repeat.  Certain others (`list' and
`x') act differently when repeated because that is more useful.

A line of input starting with `#' is a comment; it does nothing.
This is useful mainly in command files (*Note Command Files::).

GDB "prompts" for commands with a string that is normally `(gdb)'.
When debugging GDB with GDB, it is useful to change the prompt in one of
the GDBs so that you can distinguish them.  This can be done with the
`set-prompt' command.

`set-prompt NEWPROMPT'     
     Directs GDB to use NEWPROMPT as its prompt string henceforth.

To exit GDB, use the `quit' command (abbreviated `q').
`Ctrl-c' will not exit from GDB, but rather will terminate the action
of any GDB command that is in progress and return to GDB command level.
It is safe to type `Ctrl-c' at any time because GDB does not allow
it to take effect until a time when it is safe.


File: gdb  Node: Files, Prev: Input, Up: Top, Next: Switches

Specifying GDB's Files
**********************

GDB needs to know the filename of the program to be debugged.  To debug a
core dump of a previous run, GDB must be told the filename of the core
dump.

* Menu:

* Arguments: File Arguments.   Specifying files with arguments
                                (when you start GDB).
* Commands: File Commands.     Specifying files with GDB commands.


File: gdb  Node: File Arguments, Prev: Files, Up: Files, Next: File Commands

Specifying Files with Arguments
===============================

The usual way to specify the executable and core dump file names is with
two command arguments given when you start GDB.  The first argument is used
as the file for execution and symbols, and the second argument (if any) is
used as the core dump file name.  Thus,

     gdb progm core

specifies `progm' as the executable program and `core' as a core
dump file to examine.  (You do not need to have a core dump file if what
you plan to do is debug the program interactively.)

*Note Switches::, for full information on command switches and arguments for
GDB.


File: gdb  Node: File Commands, Prev: File Arguments, Up: Files

Specifying Files with Commands
==============================

Usually you specify the files for GDB to work with by giving arguments when
you invoke GDB.  But occasionally it is necessary to change to a different
file during a GDB session.  Or you may run GDB and forget to specify the
files you want to use.  In these situations the GDB commands to specify new
files are useful.

`exec-file FILENAME'     
     Specify that the program to be run is found in FILENAME.  If you
     do not specify a directory and the file is not found in GDB's working
     directory, GDB will use the environment variable `PATH' as a list
     of directories to search, just as the shell does when looking for a
     program to run.
     
`symbol-file FILENAME'     
     Read symbol table information from file FILENAME.  `PATH'
     is searched when necessary.  Most of the time you will use both the
     `exec-file' and `symbol-file' commands on the same file.
     
     `symbol-file' with no argument clears out GDB's symbol table.
     
`core-file FILENAME'     
     Specify the whereabouts of a core dump file to be used as the
     "contents of memory".  Note that the core dump contains only the
     writable parts of memory; the read-only parts must come from the
     executable file.
     
     `core-file' with no argument specifies that no core file is
     to be used.
     
`kill'     
     Cancel running the program under GDB.  This could be used if you wish
     to debug a core dump instead.  GDB ignores any core dump file if it is
     actually running the program, so the `kill' command is the only
     sure way to go back to using the core dump file.
     
`info files'     
     Print the names of the executable and core dump files currently in
     use by GDB, and the file from which symbols were loaded.

While all three file-specifying commands allow both absolute and relative
file names as arguments, GDB always converts the file name to an absolute
one and remembers it that way.

The `symbol-file' command causes GDB to forget the contents of its
convenience variables, the value history, and all breakpoints and
auto-display expressions.  This is because they may contain pointers to the
internal data recording symbols and data types, which are part of the old
symbol table data being discarded inside GDB.


File: gdb  Node: Switches, Prev: Files, Up: Top, Next: Running

Switches and Arguments for GDB
******************************

When you invoke GDB, you can pass commands telling it what files to
operate on and what other things to do.


Mode Switches
=============

`-nx'     
     Do not execute commands from the init files `.gdbinit'.
     Normally, the commands in these files are executed after all the
     command switches and arguments have been processed.  *Note Command Files::.
     
`-q'     
     "Quiet".  Do not print the usual introductory messages.
     
`-batch'     
     Run in batch mode.  Exit with code 1 after processing all the command
     files specified with `-x' (and `./.gdbinit', if not inhibited).
     Exit also if, due to an error, GDB would otherwise attempt to read a
     command from the terminal.


File-specifying Switches
========================

All the switches and command line arguments given are processed
in sequential order.  The order makes a difference when the
`-x' command is used.

`-s FILE'     
     Read symbol table from file FILE.
     
`-e FILE'     
     Use file FILE as the executable file to execute when
     appropriate, and for examining pure data in conjunction with a core
     dump.
     
`-se FILE'     
     Read symbol table from file FILE and use it as the executable
     file.
     
`-c FILE'     
     Use file FILE as a core dump to examine.
     
`-x FILE'     
     Execute GDB commands from file FILE.
     
`-d DIRECTORY'     
     Add DIRECTORY to the path to search for source files.


Other Arguments
===============

If there are arguments to GDB that are not switches or associated with
switches, the first one specifies the symbol table and executable file name
(as if it were preceded by `-se') and the second one specifies a core
dump file name (as if it were preceded by `-c').


File: gdb  Node: Running, Prev: Switches, Up: Top, Next: Stopping

Running Your Program Under GDB
******************************

To start your program under GDB, use the `run' command.  The program
must already have been specified using the `exec-file' command or with
an argument to GDB (*Note Files::); what `run' does is create an
inferior process, load the program into it, and set it in motion.

The execution of a program is affected by certain information it receives
from its superior.  GDB provides ways to specify them, which you must do
before starting the program.  (You can change them after starting the
program, but such changes do not affect the program unless you start it
over again.)

The arguments.     
     You specify the arguments to give the program as the arguments of the
     `run' command.
     
The environment.     
     The program normally inherits its environment from GDB, but you can
     use the GDB commands `set-environment' and `unset-environment' to
     change parts of the environment that will be given to the program.
     
The working directory.     
     The program inherits its working directory from GDB.  You can set GDB's
     working directory with the `cd' command in GDB.

After the `run' command, the debugger does nothing but wait for your
program to stop.  *Note Stopping::.

* Menu:

* Arguments::          Specifying the arguments for your program.
* Environment::        Specifying the environment for your program.
* Working Directory::  Specifying the working directory for giving
                       to your program when it is run.


File: gdb  Node: Arguments, Prev: Running, Up: Running, Next: Environment

Your Program's Arguments
========================

You specify the arguments to give the program as the arguments of the
`run' command.  They are passed to a shell, which expands wildcard
characters and performs redirection of I/O, and thence to the program.

`run' with no arguments uses the same arguments used by the previous
`run'.

The command `set-args' can be used to specify the arguments to be used
the next time the program is run.  If `set-args' has no arguments, it
means to use no arguments the next time the program is run.  If you have
run your program with arguments and want to run it again with no arguments,
this is the only way to do so.


File: gdb  Node: Environment, Prev: Arguments, Up: Running, Next: Working Directory

Your Program's Environment
==========================

The "environment" consists of a set of "environment variables" and
their values.  Environment variables conventionally record such things as
your user name, your home directory, your terminal type, and your search
path for programs to run.  Usually you set up environment variables with
the shell and they are inherited by all the other programs you run.  When
debugging, it can be useful to try running the program with different
environments without having to start the debugger over again.

`info environment VARNAME'     
     Print the value of environment variable VARNAME to be given to
     your program when it is started.  This command can be abbreviated
     `i env VARNAME'.
     
`info environment'     
     Print the names and values of all environment variables to be given to
     your program when it is started.  This command can be abbreviated
     `i env'.
     
`set-environment VARNAME VALUE'     
     Sets environment variable VARNAME to VALUE, for your
     program only, not for GDB itself.  VALUE may be any string; the
     values of environment variables are just strings, and any
     interpretation is supplied by your program itself.  This command
     can be abbreviated as short as `set-e'.
     
`unset-environment VARNAME'     
     Remove variable VARNAME from the environment to be passed to
     your program.  This is different from `set-env VARNAME ='
     because `unset-environment' makes a variable not be defined at
     all, which is distinguishable from an empty value.  This command can
     be abbreviated `unset'.


File: gdb  Node: Working Directory, Prev: Environment, Up: Running

Your Program's Working Directory
================================

Each time you start your program with `run', it inherits its working
directory from the current working directory of GDB.  GDB's working
directory is initially whatever it inherited from its superior, but you can
specify the working directory for GDB with the `cd' command.

The GDB working directory also serves as a default for the commands
that specify files for GDB to operate on.  *Note Files::.

`cd DIRECTORY'     
     Set GDB's working directory to DIRECTORY.
     
`pwd'     
     Print GDB's working directory.


File: gdb  Node: Stopping, Prev: Running, Up: Top, Next: Stack

Stopping and Continuing
***********************

When you run a program normally, it runs until exiting.  The purpose
of using a debugger is so that you can stop it before that point;
or so that if the program runs into trouble you can find out why.

* Menu:

* Signals::      Fatal signals in your program just stop it;
                 then you can use GDB to see what is going on.
* Breakpoints::  Breakpoints let you stop your program when it
                 reaches a specified point in the code.
* Continuing::   Resuming execution until the next signal or breakpoint.
* Stepping::     Stepping runs the program a short distance and
                 then stops it wherever it has come to.


File: gdb  Node: Signals, Prev: Stopping, Up: Stopping, Next: Breakpoints

Signals
=======

A signal is an asynchronous event that can happen in a program.  The
operating system defines the possible kinds of signals, and gives each kind
a name and a number.  For example, `SIGINT' is the signal a program
gets when you type `Ctrl-c'; `SIGSEGV' is the signal a program
gets from referencing a place in memory far away from all the areas in use;
`SIGALRM' occurs when the alarm clock timer goes off (which happens
only if the program has requested an alarm).

Some signals, including `SIGALRM', are a normal part of the
functioning of the program.  Others, such as `SIGSEGV', indicate
errors; these signals are "fatal" (kill the program immediately) if the
program has not specified in advance some other way to handle the signal.
`SIGINT' does not indicate an error in the program, but it is normally
fatal so it can carry out the purpose of `Ctrl-c': to kill the program.

GDB has the ability to detect any occurrence of a signal in the program
running under GDB's control.  You can tell GDB in advance what to do for
each kind of signal.

Normally, GDB is set up to ignore non-erroneous signals like `SIGALRM'
(so as not to interfere with their role in the functioning of the program)
but to stop the program immediately whenever an error signal happens.
You can change these settings with the `handle' command.  You must
specify which signal you are talking about with its number.

`info signal'     
     Print a table of all the kinds of signals and how GDB has been told to
     handle each one.  You can use this to see the signal numbers of all
     the defined types of signals.
     
`handle SIGNALNUM KEYWORDS...'     
     Change the way GDB handles signal SIGNALNUM.  The KEYWORDS
     say what change to make.

To use the `handle' command you must know the code number of the
signal you are concerned with.  To find the code number, type `info
signal' which prints a table of signal names and numbers.

The keywords allowed by the handle command can be abbreviated.  Their full
names are

`stop'     
     GDB should stop the program when this signal happens.  This implies
     the `print' keyword as well.
     
`print'     
     GDB should print a message when this signal happens.
     
`nostop'     
     GDB should not stop the program when this signal happens.  It may
     still print a message telling you that the signal has come in.
     
`noprint'     
     GDB should not mention the occurrence of the signal at all.  This
     implies the `nostop' keyword as well.
     
`pass'     
     GDB should allow the program to see this signal; the program will be
     able to handle the signal, or may be terminated if the signal is fatal
     and not handled.
     
`nopass'     
     GDB should not allow the program to see this signal.

When a signal has been set to stop the program, the program cannot see the
signal until you continue.  It will see the signal then, if `pass' is
in effect for the signal in question at that time.  In other words,
after GDB reports a signal, you can use the `handle' command with
`pass' or `nopass' to control whether that signal will be seen by
the program when you later continue it.

You can also use the `signal' command to prevent the program from
seeing a signal, or cause it to see a signal it normally would not see,
or to give it any signal at any time.  *Note Signaling::.


File: gdb  Node: Breakpoints, Prev: Signals, Up: Stopping, Next: Continuing

Breakpoints
===========

A "breakpoint" makes your program stop whenever a certain point in the
program is reached.  You set breakpoints explicitly with GDB commands,
specifying the place where the program should stop by line number, function
name or exact address in the program.  You can add various other conditions
to control whether the program will stop.

Each breakpoint is assigned a number when it is created; these numbers are
successive integers starting with 1.  In many of the commands for controlling
various features of breakpoints you use the breakpoint number to say which
breakpoint you want to change.  Each breakpoint may be "enabled" or
"disabled"; if disabled, it has no effect on the program until you
enable it again.

The command `info break' prints a list of all breakpoints set and not
cleared, showing their numbers, where in the program they are, and any
special features in use for them.  Disabled breakpoints are included in the
list, but marked as disabled.  `info break' with a breakpoint number
as argument lists only that breakpoint.  The convenience variable `$_'
and the default examining-address for the `x' command are set to the
address of the last breakpoint listed (*Note Memory::).

* Menu:

* Set Breaks::     How to establish breakpoints.
* Clear Breaks::   How to remove breakpoints no longer needed.
* Disabling::      How to disable breakpoints (turn them off temporarily).
* Conditions::     Making extra conditions on whether to stop.
* Break Commands:: Commands to be executed at a breakpoint.
* Error in Breakpoints:: "Cannot insert breakpoints" error--why, what to do.


File: gdb  Node: Set Breaks, Prev: Breakpoints, Up: Breakpoints, Next: Clear Breaks

Setting Breakpoints
-------------------

Breakpoints are set with the `break' command (abbreviated `b').
You have several ways to say where the breakpoint should go.

`break FUNCTION'     
     Set a breakpoint at entry to function FUNCTION.
     
`break LINENUM'     
     Set a breakpoint at line LINENUM in the current source file.
     That file is the last file whose source text was printed.  This
     breakpoint will stop the program just before it executes any of the
     code on that line.
     
`break FILENAME:LINENUM'     
     Set a breakpoint at line LINENUM in source file FILENAME.
     
`break FILENAME:FUNCTION'     
     Set a breakpoint at entry to function FUNCTION found in file
     FILENAME.  Specifying a filename as well as a function name is
     superfluous except when multiple files contain similarly named
     functions.
     
`break *ADDRESS'     
     Set a breakpoint at address ADDRESS.  You can use this to set
     breakpoints in parts of the program which do not have debugging
     information or source files.
     
`break'     
     Set a breakpoint at the next instruction to be executed in the
     selected stack frame (*Note Stack::).  This is a silly thing to do in
     the innermost stack frame because the program would stop immediately
     after being started, but it is very useful with another stack frame,
     because it will cause the program to stop as soon as control returns
     to that frame.
     
`break ... if COND'     
     Set a breakpoint with condition COND; evaluate the expression
     COND each time the breakpoint is reached, and stop only if the
     value is nonzero.  `...' stands for one of the possible
     arguments described above (or no argument) specifying where to break.
     *Note Conditions::, for more information on breakpoint conditions.
     
`tbreak ARGS'     
     Set a breakpoint enabled only for one stop.  ARGS are the
     same as in the `break' command, and the breakpoint is set in the same
     way, but the breakpoint is automatically "disabled" the first time it
     is hit.

There is no problem with setting more than one breakpoint at the same
place, but this only becomes useful when the breakpoints are conditional
(*Note Conditions::).


File: gdb  Node: Clear Breaks, Prev: Set Breaks, Up: Breakpoints, Next: Disabling

Clearing Breakpoints
--------------------

It is often necessary to eliminate a breakpoint once it has done its job
and you no longer want the program to stop there.  This is called
"clearing" or `deleting' the breakpoint.  A breakpoint that
has been cleared no longer exists in any sense.

With the `clear' command you can clear breakpoints according to where
they are in the program.  With the `delete' command you can clear
individual breakpoints by specifying their breakpoint numbers.

It is not necessary to clear a breakpoint to proceed past it.  GDB
automatically ignores breakpoints in the first instruction to be executed
when you continue execution at the same address where the program stopped.

`clear'     
     Clear any breakpoints at the next instruction to be executed in the
     selected stack frame (*Note Selection::).  When the innermost frame
     is selected, this is a good way to clear a breakpoint that the program
     just stopped at.
     
`clear FUNCTION'     
`clear FILENAME:FUNCTION'     
     Clear any breakpoints set at entry to the function FUNCTION.
     
`clear LINENUM'     
`clear FILENAME:LINENUM'     
     Clear any breakpoints set at or within the code of the specified line.
     
`delete BNUMS...'     
     Delete the breakpoints of the numbers specified as arguments.
     A breakpoint deleted is forgotten completely.


File: gdb  Node: Disabling, Prev: Clear Breaks, Up: Breakpoints, Next: Conditions

Disabling Breakpoints
---------------------

Rather than clearing a breakpoint, you might prefer to "disable" it.
This makes the breakpoint inoperative as if it had been cleared, but
remembers the information on the breakpoint so that you can "enable"
it again later.

You disable and enable breakpoints with the `enable' and
`disable' commands, specifying one or more breakpoint numbers as
arguments.  Use `info break' to print a list of breakpoints if you
don't know which breakpoint numbers to use.

A breakpoint can have any of four different states of enablement:

   * Enabled.  The breakpoint will stop the program.  A breakpoint made
     with the `break' command starts out in this state.
   * Disabled.  The breakpoint has no effect on the program.
   * Enabled once.  The breakpoint will stop the program, but
     when it does so it will become disabled.  A breakpoint made
     with the `tbreak' command starts out in this state.
   * Enabled for deletion.  The breakpoint will stop the program, but
     immediately after it does so it will be deleted permanently.

You change the state of enablement of a breakpoint with the following
commands:

`disable BNUMS...'     
     Disable the specified breakpoints.  A disabled breakpoint has no
     effect but is not forgotten.  All options such as ignore-counts,
     conditions and commands are remembered in case the breakpoint is
     enabled again later.
     
`enable BNUMS...'     
     Enable the specified breakpoints.  They become effective once again in
     stopping the program, until you specify otherwise.
     
`enable once BNUMS...'     
     Enable the specified breakpoints temporarily.  Each will be disabled
     again the next time it stops the program (unless you have used one of
     these commands to specify a different state before that time comes).
     
`enable delete BNUMS...'     
     Enable the specified breakpoints to work once and then die.  Each of
     the breakpoints will be deleted the next time it stops the program
     (unless you have used one of these commands to specify a different
     state before that time comes).

Aside from the automatic disablement or deletion of a breakpoint when it
stops the program, which happens only in certain states, the state of
enablement of a breakpoint changes only when one of the commands above
is used.


File: gdb  Node: Conditions, Prev: Disabling, Up: Breakpoints, Next: Break Commands

Break Conditions
----------------

The simplest sort of breakpoint breaks every time the program reaches a
specified place.  You can also specify a "condition" for a breakpoint.
A condition is just a boolean expression in your programming language.
A breakpoint with a condition evaluates the expression each time the
program reaches it, and the program stops only if the condition is true.

Break conditions may have side effects, and may even call functions in your
program.  These may sound like strange things to do, but their effects are
completely predictable unless there is another enabled breakpoint at the
same address.  (In that case, GDB might see the other breakpoint first and
stop the program without checking the condition of this one.)  Note that
breakpoint commands are usually more convenient and flexible for the
purpose of performing side effects when a breakpoint is reached
(*Note Break Commands::).

Break conditions can be specified when a breakpoint is set, by using
`if' in the arguments to the `break' command.  *Note Set Breaks::.
They can also be changed at any time with the `condition' command:

`condition BNUM EXPRESSION'     
     Specify EXPRESSION as the break condition for breakpoint number
     BNUM.  From now on, this breakpoint will stop the program only if
     the value of EXPRESSION is true (nonzero, in C).  EXPRESSION
     is not evaluated at the time the `condition' command is given.
     
`condition BNUM'     
     Remove the condition from breakpoint number BNUM.  It becomes
     an ordinary unconditional breakpoint.

A special feature is provided for one kind of condition: to prevent the
breakpoint from doing anything until it has been reached a certain number
of times.  This is done with the "ignore count" of the breakpoint.
When the program reaches a breakpoint whose ignore count is positive, then
instead of stopping, it just decrements the ignore count by one and
continues.

`ignore BNUM COUNT'     
     Set the ignore count of breakpoint number BNUM to COUNT.
     The next COUNT times the breakpoint is reached, it will not stop.
     
     To make the breakpoint stop the next time it is reached, specify
     a count of zero.
     
`cont COUNT'     
     Continue execution of the program, setting the ignore count of the
     breakpoint that the program stopped at to COUNT minus one.
     Continuing through the breakpoint does not itself count as one of
     COUNT.  Thus, the program will not stop at this breakpoint until the
     COUNT'th time it is hit.
     
     This command is allowed only when the program stopped due to a
     breakpoint.  At other times, the argument to `cont' is ignored.

If a breakpoint has a positive ignore count and a condition, the condition
is not checked.  Once the ignore count reaches zero, the condition will
start to be checked.

Note that you could achieve the effect of the ignore count with a condition
such as `$foo-- <= 0' using a debugger convenience variable that is
decremented each time.  That is why the ignore count is considered a
special case of a condition.  *Note Convenience Vars::.


File: gdb  Node: Break Commands, Prev: Conditions, Up: Breakpoints, Next: Error in Breakpoints

Commands Executed on Breaking
-----------------------------

You can give any breakpoint a series of commands to execute when the
program stops due to that breakpoint.  For example, you might want to
print the values of certain expressions, or enable other breakpoints.

`commands BNUM'     
     Specify commands for breakpoint number BNUM.  The commands
     themselves appear on the following lines.  Type a line containing just
     `end' to terminate the commands.
     
     To remove all commands from a breakpoint, use the command
     `commands' and follow it immediately by `end'; that is, give
     no commands.

It is possible for breakpoint commands to start the program up again.
Simply use the `cont' command, or `step', or any other command
to resume execution.  However, any remaining breakpoint commands are
ignored.  When the program stops again, GDB will act according to why
that stop took place.

If the first command specified is `silent', the usual message about
stopping at a breakpoint is not printed.  This may be desirable for
breakpoints that are to print a specific message and then continue.
If the remaining commands too print nothing, you will see no sign that
the breakpoint was reached at all.  `silent' is not really a command;
it is meaningful only at the beginning of the commands for a breakpoint.

The commands `echo' and `output' that allow you to print precisely
controlled output are often useful in silent breakpoints.  *Note Output::.

For example, here is how you could use breakpoint commands to print the
value of `x' at entry to `foo' whenever it is positive.  We
assume that the newly created breakpoint is number 4; `break' will
print the number that is assigned.

     break foo if x>0
     commands 4
     silent
     echo x is\040
     output x
     echo \n
     cont
     end

One application for breakpoint commands is to correct one bug so you can
test another.  Put a breakpoint just after the erroneous line of code, give
it a condition to detect the case in which something erroneous has been
done, and give it commands to assign correct values to any variables that
need them.  End with the `cont' command so that the program does not
stop, and start with the `silent' command so that no output is
produced.  Here is an example:

     break 403
     commands 5
     silent
     set x = y + 4
     cont
     end

One deficiency in the operation of automatically continuing breakpoints
under Unix appears when your program uses raw mode for the terminal.
GDB switches back to its own terminal modes (not raw) before executing
commands, and then must switch back to raw mode when your program is
continued.  This causes any pending terminal input to be lost.

In the GNU system, this will be fixed by changing the behavior of
terminal modes.

Under Unix, when you have this problem, you might be able to get around
it by putting your actions into the breakpoint condition instead of
commands.  For example

     condition 5  (x = y + 4), 0

is a condition expression that will change `x' as needed, then always
have the value 0 so the program will not stop.  Loss of input is avoided
here because break conditions are evaluated without changing the terminal
modes.  When you want to have nontrivial conditions for performing the side
effects, the operators `&&', `||' and `? ... :' may be useful.


File: gdb  Node: Error in Breakpoints, Prev: Break Commands, Up: Breakpoints

"Cannot Insert Breakpoints" Error
---------------------------------

Under Unix, breakpoints cannot be used in a program if any other process
is running that program.  Attempting to run or continue the program with
a breakpoint in this case will cause GDB to stop it.

When this happens, you have two ways to proceed:

  1. Remove or disable the breakpoints, then continue.
     
  2. Suspend GDB, and copy the file containing the program to a new name.
     Resume GDB and use the `exec-file' command to specify that GDB
     should run the program under that name.  Then start the program again.


File: gdb  Node: Continuing, Prev: Breakpoints, Up: Stopping, Next: Stepping

Continuing
==========

After your program stops, most likely you will want it to run some more if
the bug you are looking for has not happened yet.

`cont'     
     Continue running the program at the place where it stopped.

If the program stopped at a breakpoint, the place to continue running
is the address of the breakpoint.  You might expect that continuing would
just stop at the same breakpoint immediately.  In fact, `cont'
takes special care to prevent that from happening.  You do not need
to clear the breakpoint to proceed through it after stopping at it.

You can, however, specify an ignore-count for the breakpoint that the
program stopped at, by means of an argument to the `cont' command.
*Note Conditions::.

If the program stopped because of a signal other than `SIGINT' or
`SIGTRAP', continuing will cause the program to see that signal.
You may not want this to happen.  For example, if the program stopped
due to some sort of memory reference error, you might store correct
values into the erroneous variables and continue, hoping to see more
execution; but the program would probably terminate immediately as
a result of the fatal signal once it sees the signal.  To prevent this,
you can continue with `signal 0'.  *Note Signaling::.  You can
also act in advance to prevent the program from seeing certain kinds
of signals, using the `handle' command (*Note Signals::).


File: gdb  Node: Stepping, Prev: Continuing, Up: Stopping

Stepping
========

"Stepping" means setting your program in motion for a limited time, so
that control will return automatically to the debugger after one line of
code or one machine instruction.  Breakpoints are active during stepping
and the program will stop for them even if it has not gone as far as the
stepping command specifies.

`step'     
     Proceed the program until control reaches a different line, then stop
     it and return to the debugger.  This command is abbreviated `s'.
     
`step COUNT'     
     Proceed as in `step', but do so COUNT times.  If a breakpoint
     or a signal not related to stepping is reached before COUNT steps,
     stepping stops right away.
     
`next'     
     Similar to `step', but any function calls appearing within the line of
     code are executed without stopping.  Execution stops when control reaches a
     different line of code at the stack level which was executing when the
     `next' command was given.  This command is abbreviated `n'.
     
     An argument is a repeat count, as in `step'.
     
`finish'     
     Continue running until just after the selected stack frame returns
     (or until there is some other reason to stop, such as a fatal signal
     or a breakpoint).
     
     Contrast this with the `return' command (*Note Returning::).
     
`stepi'     
`si'     
     Proceed one machine instruction, then stop and return to the debugger.
     
     It is often useful to do `display/i $pc' when stepping by machine
     instructions.  This will cause the next instruction to be executed to
     be displayed automatically at each stop.  *Note Auto Display::.
     
     An argument is a repeat count, as in `step'.
     
`nexti'     
`ni'     
     Proceed one machine instruction, but if it is a subroutine call,
     proceed until the subroutine returns.
     
     An argument is a repeat count, as in `next'.

A typical technique for using stepping is to put a breakpoint
(*Note Breakpoints::) at the beginning of the function or the section of
the program in which a problem is believed to lie, and then step through
the suspect area, examining the variables that are interesting, until the
problem happens.

The `cont' command can be used after stepping to resume execution
until the next breakpoint or signal.


File: gdb  Node: Stack, Prev: Stopping, Up: Top, Next: Source

Examining the Stack
*******************

When your program has stopped, the first thing you need to know is where it
stopped and how it got there.

Each time your program performs a function call, the information about
where in the program the call was made from is saved in a block of data
called a "stack frame".  The frame also contains the arguments of the
call and the local variables of the function that was called.  All the
stack frames are allocated in a region of memory called the "call
stack".

When your program stops, the GDB commands for examining the stack allow you
to see all of this information.

One of the stack frames is "selected" by GDB and many GDB commands
refer implicitly to the selected frame.  In particular, whenever you ask
GDB for the value of a variable in the program, the value is found in the
selected frame.  There are special GDB commands to select whichever frame
you are interested in.

When the program stops, GDB automatically selects the currently executing
frame and describes it briefly as the `frame' command does
(*Note Info: Frame Info.).

* Menu:

* Frames::          Explanation of stack frames and terminology.
* Backtrace::       Summarizing many frames at once.
* Selection::       How to select a stack frame.
* Info: Frame Info, Commands to print information on stack frames.


File: gdb  Node: Frames, Prev: Stack, Up: Stack, Next: Backtrace

Stack Frames
============

The call stack is divided up into contiguous pieces called "frames";
each frame is the data associated with one call to one function.  The frame
contains the arguments given to the function, the function's local
variables, and the address at which the function is executing.

When your program is started, the stack has only one frame, that of the
function `main'.  This is called the "initial" frame or the
"outermost" frame.  Each time a function is called, a new frame is
made.  Each time a function returns, the frame for that function invocation
is eliminated.  If a function is recursive, there can be many frames for
the same function.  The frame for the function in which execution is
actually occurring is called the "innermost" frame.  This is the most
recently created of all the stack frames that still exist.

Inside your program, stack frames are identified by their addresses.  A
stack frame consists of many bytes, each of which has its own address; each
kind of computer has a convention for choosing one of those bytes whose
address serves as the address of the frame.  Usually this address is kept
in a register called the "frame pointer register" while execution is
going on in that frame.

GDB assigns numbers to all existing stack frames, starting with zero for
the innermost frame, one for the frame that called it, and so on upward.
These numbers do not really exist in your program; they are to give you a
way of talking about stack frames in GDB commands.

Many GDB commands refer implicitly to one stack frame.  GDB records a stack
frame that is called the "selected" stack frame; you can select any
frame using one set of GDB commands, and then other commands will operate
on that frame.  When your program stops, GDB automatically selects the
innermost frame.


File: gdb  Node: Backtrace, Prev: Frames, Up: Stack, Next: Selection

Backtraces
==========

A backtrace is a summary of how the program got where it is.  It shows one
line per frame, for many frames, starting with the currently executing
frame (frame zero), followed by its caller (frame one), and on up the
stack.

`backtrace'     
`bt'     
     Print a backtrace of the entire stack: one line per frame for all
     frames in the stack.
     
     You can stop the backtrace at any time by typing the system interrupt
     character, normally `Control-C'.
     
`backtrace N'     
`bt N'     
     Similar, but stop after N frames.

Each line in a backtrace shows the frame number, the program counter, the
function and its arguments, and the source file name and line number (if
known).  The program counter may be omitted if it as it the beginning of
the source line.  This is the same as the first of the two lines printed
when you select a frame.


File: gdb  Node: Selection, Prev: Backtrace, Up: Stack, Next: Frame Info

Selecting a Frame
=================

Most commands for examining the stack and other data in the program work on
whichever stack frame is selected at the moment.  Here are the commands for
selecting a stack frame; all of them finish by printing a brief description
of the stack frame just selected.

`frame N'     
     Select frame number N.  Recall that frame zero is the innermost
     (currently executing) frame, frame one is the frame that called the
     innermost one, and so on.  The highest-numbered frame is `main''s
     frame.
     
`frame ADDR'     
     Select the frame at address ADDR.  This is useful mainly if the
     chaining of stack frames has been damaged by a bug, making it
     impossible for GDB to assign numbers properly to all frames.  In
     addition, this can be useful when the program has multiple stacks and
     switches between them.
     
`up N'     
     Select the frame N frames up from the frame previously selected.
     For positive numbers N, this advances toward the outermost
     frame, to higher frame numbers, to frames that have existed longer.
     N defaults to one.
     
`down N'     
     Select the frame N frames down from the frame previously
     selected.  For positive numbers N, this advances toward the
     innermost frame, to lower frame numbers, to frames that were created
     more recently.  N defaults to one.

All of these commands end by printing some information on the frame that
has been selected: the frame number, the function name, the arguments, the
source file and line number of execution in that frame, and the text of
that source line.  For example:

     #3  main (argc=3, argv=??, env=??) at main.c, line 67
     67        read_input_file (argv[i]);

After such a printout, the `list' command with no arguments will print
ten lines centered on the point of execution in the frame.  *Note List::.


File: gdb  Node: Frame Info, Prev: Selection, Up: Stack

Information on a Frame
======================

There are several other commands to print information about the selected
stack frame.

`frame'     
     This command prints a brief description of the selected stack frame.
     It can be abbreviated `f'.  With an argument, this command is
     used to select a stack frame; with no argument, it does not change
     which frame is selected, but still prints the same information.
     
`info frame'     
     This command prints a verbose description of the selected stack frame,
     including the address of the frame, the addresses of the next frame in
     (called by this frame) and the next frame out (caller of this frame),
     the address of the frame's arguments, the program counter saved in it
     (the address of execution in the caller frame), and which registers
     were saved in the frame.  The verbose description is useful when
     something has gone wrong that has made the stack format fail to fit
     the usual conventions.
     
`info frame ADDR'     
     Print a verbose description of the frame at address ADDR,
     without selecting that frame.  The selected frame remains unchanged by
     this command.
     
`info args'     
     Print the arguments of the selected frame, each on a separate line.
     
`info locals'     
     Print the local variables of the selected frame, each on a separate
     line.  These are all variables declared static or automatic within all
     program blocks that execution in this frame is currently inside of.


File: gdb  Node: Source, Prev: Stack, Up: Top, Next: Data

Examining Source Files
**********************

GDB knows which source files your program was compiled from, and
can print parts of their text.  When your program stops, GDB
spontaneously prints the line it stopped in.  Likewise, when you
select a stack frame (*Note Selection::), GDB prints the line
which execution in that frame has stopped in.  You can also
print parts of source files by explicit command.

* Menu:

* List::        Using the `list' command to print source files.
* Source Path:: Specifying the directories to search for source files.


File: gdb  Node: List, Prev: Source, Up: Source, Next: Source Path

Printing Source Lines
=====================

To print lines from a source file, use the `list' command
(abbreviated `l').  There are several ways to specify what part
of the file you want to print.

Here are the forms of `list' command most commonly used:

`list LINENUM'     
     Print ten lines centered around line number LINENUM in the
     current source file.
     
`list FUNCTION'     
     Print ten lines centered around the beginning of function
     FUNCTION.
     
`list'     
     Print ten more lines.  If the last lines printed were printed with a
     `list' command, this prints ten lines following the last lines
     printed; however, if the last line printed was a solitary line printed
     as part of displaying a stack frame (*Note Stack::), this prints ten
     lines centered around that line.
     
`list -'     
     Print ten lines just before the lines last printed.

Repeating a `list' command with RET discards the argument,
so it is equivalent to typing just `list'.  This is more useful
than listing the same lines again.  An exception is made for an
argument of `-'; that argument is preserved in repetition so that
each repetition moves up in the file.

In general, the `list' command expects you to supply zero, one or two
"linespecs".  Linespecs specify source lines; there are several ways
of writing them but the effect is always to specify some source line.
Here is a complete description of the possible arguments for `list':

`list LINESPEC'     
     Print ten lines centered around the line specified by LINESPEC.
     
`list FIRST,LAST'     
     Print lines from FIRST to LAST.  Both arguments are
     linespecs.
     
`list ,LAST'     
     Print ten lines ending with LAST.
     
`list FIRST,'     
     Print ten lines starting with FIRST.
     
`list +'     
     Print ten lines just after the lines last printed.
     
`list -'     
     Print ten lines just before the lines last printed.
     
`list'     
     As described in the preceding table.

Here are the ways of specifying a single source line---all the
kinds of linespec.

LINENUM     
     Specifies line LINENUM of the current source file.
     When a `list' command has two linespecs, this refers to
     the same source file as the first linespec.
     
+OFFSET     
     Specifies the line OFFSET lines after the last line printed.
     When used as the second linespec in a `list' command that has
     two, this specifies the line OFFSET lines down from the
     first linespec.
     
-OFFSET     
     Specifies the line OFFSET lines before the last line printed.
     
FILENAME:LINENUM     
     Specifies line LINENUM in the source file FILENAME.
     
FUNCTION     
     Specifies the line of the open-brace that begins the body of the
     function FUNCTION.
     
FILENAME:FUNCTION     
     Specifies the line of the open-brace that begins the body of the
     function FUNCTION in the file FILENAME.  The file name is
     needed with a function name only for disambiguation of identically
     named functions in different source files.
     
*ADDRESS     
     Specifies the line containing the program address ADDRESS.
     ADDRESS may be any expression.

One other command is used to map source lines to program addresses.

`info line LINENUM'     
     Print the starting and ending addresses of the compiled code for
     source line LINENUM.
     
     The default examine address for the `x' command is changed to the
     starting address of the line, so that `x/i' is sufficient to
     begin examining the machine code (*Note Memory::).  Also, this address
     is saved as the value of the convenience variable `$_'
     (*Note Convenience Vars::).


File: gdb  Node: Source Path, Prev: List, Up: Source

Specifying Source Directories
=============================

Executable programs do not record the directories of the source files they
were compiled from, just the names.  GDB remembers a list of directories to
search for source files; this is called the "source path".  Each time
GDB wants a source file, it tries all the directories in the list, in the
order they are present in the list, until it finds a file with the desired
name.

When you start GDB, its source path contains just the current working
directory.  To add other directories, use the `directory' command.
Note that the search path for executable files and the working directory
are not used for finding source files.

`directory DIRNAME'     
     Add directory DIRNAME to the end of the source path.
     
`directory'     
     Reset the source path to just the current working directory of GDB.
     This requires confirmation.
     
     `directory' with no argument can cause source files previously
     found by GDB to be found in a different directory.  To make this work
     correctly, this command also clears out the tables GDB maintains
     about the source files it has already found.
     
`info directories'     
     Print the source path: show which directories it contains.

Because the `directory' command adds to the end of the source path,
it does not affect any file that GDB has already found.  If the source
path contains directories that you do not want, and these directories
contain misleading files with names matching your source files, the
way to correct the situation is as follows:

  1. Choose the directory you want at the beginning of the source path.
     Use the `cd' command to make that the current working directory.
     
  2. Use `directory' with no argument to reset the source path to just
     that directory.
     
  3. Use `directory' with suitable arguments to add any other
     directories you want in the source path.


File: gdb  Node: Data, Prev: Source, Up: Top, Next: Symbols

Examining Data
**************

The usual way of examining data in your program is with the `print'
command (abbreviated `p').  It evaluates and prints the value of any
valid expression of the language the program is written in (for now, C).
You type

     print EXP

where EXP is any valid expression, and the value of EXP
is printed in a format appropriate to its data type.

A more low-level way of examining data is with the `x' command.
It examines data in memory at a specified address and prints it in a
specified format.

* Menu:

* Expressions::      Expressions that can be computed and printed.
* Variables::        Using your program's variables in expressions.
* Assignment::       Setting your program's variables.
* Arrays::           Examining part of memory as an array.
* Formats::          Specifying formats for printing values.
* Memory::           Examining memory explicitly.
* Auto Display::     Printing certain expressions whenever program stops.
* Value History::    Referring to values previously printed.
* Convenience Vars:: Giving names to values for future reference.
* Registers::        Referring to and storing in machine registers.


File: gdb  Node: Expressions, Prev: Data, Up: Data, Next: Variables

Expressions
===========

Many different GDB commands accept an expression and compute its value.
Any kind of constant, variable or operator defined by the programming
language you are using is legal in an expression in GDB.  This includes
conditional expressions, function calls, casts and string constants.

Casts are supported in all languages, not just in C, because it is so
useful to cast a number into pointer so as to examine a structure
at that address in memory.

GDB supports three kinds of operator in addition to those of programming
languages:

`@'     
     `@' is a binary operator for treating parts of memory as arrays.
     *Note Arrays::, for more information.
     
`::'     
     `::' allows you to specify a variable in terms of the file or
     function it is defined in.  *Note Variables::.
     
`{TYPE} ADDR'     
     Refers to an object of type TYPE stored at address ADDR in memory.
     ADDR may be any expression whose value is an integer or pointer (but
     parentheses are required around nonunary operators, just as in a
     cast).  This construct is allowed regardless of what kind of data is
     officially supposed to reside at ADDR.


File: gdb  Node: Variables, Prev: Expressions, Up: Data, Next: Arrays

Program Variables
=================

The most common kind of expression to use is the name of a variable
in your program.

Variables in expressions are understood in the selected stack frame
(*Note Selection::); they must either be global (or static) or be visible
according to the scope rules of the programming language from the point of
execution in that frame.  This means that in the function

     foo (a)
          int a;
     {
       bar (a);
       {
         int b = test ();
         bar (b);
       }
     }

the variable `a' is usable whenever the program is executing
within the function `foo', but the variable `b' is visible
only while the program is executing inside the block in which `b'
is declared.


File: gdb  Node: Arrays, Prev: Variables, Up: Data, Next: Formats

Artificial Arrays
=================

It is often useful to print out several successive objects of the
same type in memory; a section of an array, or an array of
dynamically determined size for which only a pointer exists in the
program.

This can be done by constructing an "artificial array" with the
binary operator `@'.  The left operand of `@' should be
the first element of the desired array, as an individual object.
The right operand should be the length of the array.  The result is
an array value whose elements are all of the type of the left argument.
The first element is actually the left argument; the second element
comes from bytes memory immediately following those that hold the
first element, and so on.  Here is an example.  If a program says

     int *array = (int *) malloc (len * sizeof (int));

you can print the contents of `array' with

     p *array@len

The left operand of `@' must reside in memory.  Array values made
with `@' in this way behave just like other arrays in terms of
subscripting, and are coerced to pointers when used in expressions.
(It would probably appear in an expression via the value history,
after you had printed it out.)


File: gdb  Node: Formats, Prev: Arrays, Up: Data, Next: Memory

Formats
=======

GDB normally prints all values according to their data types.  Sometimes
this is not what you want.  For example, you might want to print a number
in hex, or a pointer in decimal.  Or you might want to view data in memory
at a certain address as a character string or an instruction.  These things
can be done with "output formats".

The simplest use of output formats is to say how to print a value
already computed.  This is done by starting the arguments of the
`print' command with a slash and a format letter.  The format
letters supported are:

`x'     
     Regard the bits of the value as an integer, and print the integer in
     hexadecimal.
     
`d'     
     Print as integer in signed decimal.
     
`u'     
     Print as integer in unsigned decimal.
     
`o'     
     Print as integer in octal.
     
`a'     
     Print as an address, both absolute in hex and then relative
     to a symbol defined as an address below it.
     
`c'     
     Regard as an integer and print it as a character constant.
     
`f'     
     Regard the bits of the value as a floating point number and print
     using typical floating point syntax.

For example, to print the program counter in hex (*Note Registers::), type

     p/x $pc

Note that no space is required before the slash; this is because command
names in GDB cannot contain a slash.

To reprint the last value in the value history with a different format,
you can use the `print' command with just a format and no
expression.  For example, `p/x' reprints the last value in hex.


File: gdb  Node: Memory, Prev: Formats, Up: Data, Next: Auto Display

Examining Memory
----------------

The command `x' (for `examine') can be used to examine memory under
explicit control of formats, without reference to the program's data types.

`x' is followed by a slash and an output format specification,
followed by an expression for an address.  The expression need not have
a pointer value (though it may); it is used as an integer, as the
address of a byte of memory.

The output format in this case specifies both how big a unit of memory
to examine and how to print the contents of that unit.  It is done
with one or two of the following letters:

These letters specify just the size of unit to examine:

`b'     
     Examine individual bytes.
     
`h'     
     Examine halfwords (two bytes each).
     
`w'     
     Examine words (four bytes each).
     
     Many assemblers and cpu designers still use `word' for a 16-bit quantity,
     as a holdover from specific predecessor machines of the 1970's that really
     did use two-byte words.  But more generally the term `word' has always
     referred to the size of quantity that a machine normally operates on and
     stores in its registers.  This is 32 bits for all the machines that GNU
     runs on.
     
`g'     
     Examine giant words (8 bytes).

These letters specify just the way to print the contents:

`x'     
     Print as integers in unsigned hexadecimal.
     
`d'     
     Print as integers in signed decimal.
     
`u'     
     Print as integers in unsigned decimal.
     
`o'     
     Print as integers in unsigned octal.
     
`a'     
     Print as an address, both absolute in hex and then relative
     to a symbol defined as an address below it.
     
`c'     
     Print as character constants.
     
`f'     
     Print as floating point.  This works only with sizes `w' and
     `g'.
     
`s'     
     Print a null-terminated string of characters.  The specified unit size
     is ignored; instead, the unit is however many bytes it takes to reach
     a null character (including the null character).
     
`i'     
     Print a machine instruction in assembler syntax (or nearly).  The
     specified unit size is ignored; the number of bytes in an instruction
     varies depending on the type of machine, the opcode and the addressing
     modes used.

If either the manner of printing or the size of unit fails to be specified,
the default is to use the same one that was used last.  If you don't want
to use any letters after the slash, you can omit the slash as well.

You can also omit the address to examine.  Then the address used is
just after the last unit examined.  This is why string and instruction
formats actually compute a unit-size based on the data: so that the
next string or instruction examined will start in the right place.
The `print' command sometimes sets the default address for
the `x' command; when the value printed resides in memory, the
default is set to examine the same location.  `info line' also
sets the default for `x', to the address of the start of the
machine code for the specified line and `info breakpoints' sets
it to the address of the last breakpoint listed.

When you use RET to repeat an `x' command, it does not repeat
exactly the same: the address specified previously (if any) is ignored, so
that the repeated command examines the successive locations in memory
rather than the same ones.

You can examine several consecutive units of memory with one command by
writing a repeat-count after the slash (before the format letters, if any).
The repeat count must be a decimal integer.  It has the same effect as
repeating the `x' command that many times except that the output may
be more compact with several units per line.

     x/10i $pc

Prints ten instructions starting with the one to be executed next in the
selected frame.  After doing this, you could print another ten following
instructions with

     x/10

in which the format and address are allowed to default.

The addresses and contents printed by the `x' command are not put in
the value history because there is often too much of them and they would
get in the way.  Instead, GDB makes these values available for subsequent
use in expressions as values of the convenience variables `$_' and
`$__'.

After an `x' command, the last address examined is available for use
in expressions in the convenience variable `$_'.  The contents of that
address, as examined, are available in the convenience variable `$__'.

If the `x' command has a repeat count, the address and contents saved
are from the last memory unit printed; this is not the same as the last
address printed if several units were printed on the last line of output.


File: gdb  Node: Auto Display, Prev: Memory, Up: Data, Next: Value History

Automatic Display
=================

If you find that you want to print the value of an expression frequently
(to see how it changes), you might want to add it to the "automatic
display list" so that GDB will print its value each time the program stops.
Each expression added to the list is given a number to identify it;
to remove an expression from the list, you specify that number.
The automatic display looks like this:

     2: foo = 38
     3: bar[5] = (struct hack *) 0x3804

showing item numbers, expressions and their current values.

`display EXP'     
     Add the expression EXP to the list of expressions to display
     each time the program stops.
     
`display/FMT EXP'     
     For FMT specifying only a display format and not a size or
     count, add the expression EXP to the auto-display list but
     arranges to display it each time in the specified format FMT,
     
`display/FMT ADDR'     
     For FMT `i' or `s', or including a unit-size or a
     number of units, add the expression ADDR as a memory address to
     be examined each time the program stops.  Examining means in effect
     doing `x/FMT ADDR'.  *Note Memory::.
     
`undisplay N'     
     Remove item number N from the list of expressions to display.
     
`display'     
     Display the current values of the expressions on the list, just as is
     done when the program stops.
     
`info display'     
     Print the list of expressions to display automatically, each one
     with its item number, but without showing the values.


File: gdb  Node: Value History, Prev: Auto Display, Up: Data, Next: Convenience Vars

Value History
=============

Every value printed by the `print' command is saved for the entire
session in GDB's "value history" so that you can refer to it in
other expressions.

The values printed are given "history numbers" for you to refer to them
by.  These are successive integers starting with 1.  `print' shows you
the history number assigned to a value by printing `$N = '
before the value; here N is the history number.

To refer to any previous value, use `$' followed by the value's
history number.  The output printed by `print' is designed to remind
you of this.  Just `$' refers to the most recent value in the history,
and `$$' refers to the value before that.

For example, suppose you have just printed a pointer to a structure and
want to see the contents of the structure.  It suffices to type

     p *$

If you have a chain of structures where the component `next' points
to the next one, you can print the contents of the next one with

     p *$.next

It might be useful to repeat this command many times by typing RET.

Note that the history records values, not expressions.  If the value of
`x' is 4 and you type

     print x
     set x=5

then the value recorded in the value history by the `print' command
remains 4 even though `x''s value has changed.

`info history'     
     Print the last ten values in the value history, with their item
     numbers.  This is like `p $$9' repeated ten times, except that
     `info history' does not change the history.
     
`info history N'     
     Print ten history values centered on history item number N.


File: gdb  Node: Convenience Vars, Prev: Value History, Up: Data, Next: Registers

Convenience Variables
=====================

GDB provides "convenience variables" that you can use within GDB to
hold on to a value and refer to it later.  These variables exist entirely
within GDB; they are not part of your program, and setting a convenience
variable has no effect on further execution of your program.  That's why
you can use them freely.

Convenience variables have names starting with `$'.  Any name starting
with `$' can be used for a convenience variable, unless it is one of
the predefined set of register names (*Note Registers::).

You can save a value in a convenience variable with an assignment
expression, just as you would set a variable in your program.  Example:

     set $foo = *object_ptr

would save in `$foo' the value contained in the object pointed to by
`object_ptr'.

Using a convenience variable for the first time creates it; but its value
is `void' until you assign a new value.  You can alter the value with
another assignment at any time.

Convenience variables have no fixed types.  You can assign a convenience
variable any type of value, even if it already has a value of a different
type.  The convenience variable as an expression has whatever type its
current value has.

`info convenience'     
     Print a list of convenience variables used so far, and their values.
     Abbreviated `i con'.

One of the ways to use a convenience variable is as a counter to be
incremented or a pointer to be advanced.  For example:

     set $i = 0
     print bar[$i++]->contents
     ...repeat that command by typing RET.

Some convenience variables are created automatically by GDB and given
values likely to be useful.

`$_'     
     The variable `$_' is automatically set by the `x' command to
     the last address examined (*Note Memory::).  Other commands which
     provide a default address for `x' to examine also set `$_'
     to that address; these commands include `info line' and `info
     breakpoint'.
     
`$__'     
     The variable `$__' is automatically set by the `x' command
     to the value found in the last address examined.


File: gdb  Node: Registers, Prev: Convenience Vars, Up: Data

Registers
=========

Machine register contents can be referred to in expressions as variables
with names starting with `$'.  The names of registers are different
for each machine; use `info registers' to see the names used on your
machine.  The names `$pc' and `$sp' are used on all machines for
the program counter register and the stack pointer.  Often `$fp' is
used for a register that contains a pointer to the current stack frame.

GDB always considers the contents of an ordinary register as an integer
when the register is examined in this way.  Programs can store floating
point values in registers also, but there is currently no GDB command
to examine a specified register in floating point.  (However, if the
variable in your program which is stored in the register is a floating
point variable, you can see the floating point value by examining
the variable.)

Some machines have special floating point registers.  GDB considers these
registers' values as floating point when you examine them explicitly.

Some registers have distinct "raw" and "virtual" data formats.  This
means that the data format in which the register contents are saved by the
operating system is not the same one that your program normally sees.  For
example, the registers of the 68881 floating point coprocessor are always
saved in "extended" format, but all C programs expect to work with
"double" format.  In such cases, GDB normally works with the virtual
format only (the format that makes sense for your program), but the
`info registers' command prints the data in both formats.

Register values are relative to the selected stack frame
(*Note Selection::).  This means that you get the value that the register
would contain if all stack frames farther in were exited and their saved
registers restored.  In order to see the real contents of all registers,
you must select the innermost frame (with `frame 0').

Some registers are never saved (typically those numbered zero or one)
because they are used for returning function values; for these registers,
relativization makes no difference.

`info registers'     
     Print the names and relativized values of all registers.
     
`info registers REGNAME'     
     Print the relativized value of register REGNAME.  REGNAME
     may be any register name valid on the machine you are using, with
     or without the initial `$'.


Examples
--------

You could print the program counter in hex with

     p/x $pc

or print the instruction to be executed next with

     x/i $pc

or add four to the stack pointer with

     set $sp += 4

The last is a way of removing one word from the stack, on machines where
stacks grow downward in memory (most machines, nowadays).  This assumes
that the innermost stack frame is selected.  Setting `$sp' is
not allowed when other stack frames are selected.


File: gdb  Node: Symbols, Prev: Data, Up: Top, Next: Altering

Examining the Symbol Table
**************************

The commands described in this section allow you to make inquiries for
information about the symbols (names of variables, functions and types)
defined in your program.  This information is found by GDB in the symbol
table loaded by the `symbol-file' command; it is inherent in the text
of your program and does not change as the program executes.

`whatis EXP'     
     Print the data type of expression EXP.  EXP is not
     actually evaluated, and any side-effecting operations (such as
     assignments or function calls) inside it do not take place.
     
`whatis'     
     Print the data type of `$', the last value in the value history.
     
`info address SYMBOL'     
     Describe where the data for SYMBOL is stored.  For register
     variables, this says which register.  For other automatic variables,
     this prints the stack-frame offset at which the variable is always
     stored.  Note the contrast with `print &SYMBOL', which does
     not work at all for register variables and for automatic variables
     prints the exact address of the current instantiation of the variable.
     
`ptype TYPENAME'     
     Print a description of data type TYPENAME.  TYPENAME may be the name
     of a type, or for C code it may have the form `struct STRUCT-TAG',
     `union UNION-TAG' or `enum ENUM-TAG'.
     
`info sources'     
     Print the names of all source files in the program for which there
     is debugging information.
     
`info functions'     
     Print the names and data types of all defined functions.
     
`info functions REGEXP'     
     Print the names and data types of all defined functions
     whose names contain a match for regular expression REGEXP.
     Thus, `info fun step' finds all functions whose names
     include `step'; `info fun ^step' finds those whose names
     start with `step'.
     
`info variables'     
     Print the names and data types of all variables that are declared
     outside of functions.
     
`info variables REGEXP'     
     Print the names and data types of all variables, declared outside of
     functions, whose names contain a match for regular expression
     REGEXP.
     
`info types'     
     Print all data types that are defined in the program.
     
`info types REGEXP'     
     Print all data types that are defined in the program whose names
     contain a match for regular expression REGEXP.
     
`printsyms FILENAME'     
     Write a complete dump of the debugger's symbol data into the
     file FILENAME.


File: gdb  Node: Altering, Prev: Symbols, Up: Top, Next: Sequences

Altering Execution
******************

There are several ways to alter the execution of your program with GDB
commands.

* Menu:

* Assignment::    Altering variable values or memory contents.
* Jumping::       Altering control flow.
* Signaling::     Making signals happen in the program.
* Returning::     Making a function return prematurely.


File: gdb  Node: Assignment, Prev: Altering, Up: Altering, Next: Jumping

Assignment to Variables
=======================

To alter the value of a variable, evaluate an assignment expression.
For example,

     print x=4

would store the value 4 into the variable `x', and then print
the value of the assignment expression (which is 4).

If you are not interested in seeing the value of the assignment, use the
`set' command instead of the `print' command.  `set' is
really the same as `print' except that the expression's value is not
printed and is not put in the value history (*Note Value History::).  The
expression is evaluated only for side effects.

GDB allows more implicit conversions in assignments than C does; you can
freely store an integer value into a pointer variable or vice versa, and
any structure can be converted to any other structure that is the same
length or shorter.

In C, all the other assignment operators such as `+=' and `++'
are supported as well.

To store into arbitrary places in memory, use the `{...}'
construct to generate a value of specified type at a specified address
(*Note Expressions::).  For example,

     set {int}0x83040 = 4


File: gdb  Node: Jumping, Prev: Assignment, Up: Altering, Next: Signaling

Continuing at a Different Address
=================================

`jump LINENUM'     
     Resume execution at line number LINENUM.  Execution may stop
     immediately if there is a breakpoint there.
     
     The `jump' command does not change the current stack frame, or
     the stack pointer, or the contents of any memory location or any
     register other than the program counter.  If line LINENUM is in
     a different function from the one currently executing, the results may
     be wild if the two functions expect different patterns of arguments or
     of local variables.  For his reason, the `jump' command requests
     confirmation if the specified line is not in the function currently
     executing.  However, even wild results are predictable based on
     changing the program counter.
     
`jump *ADDRESS'     
     Resume execution at the instruction at address ADDRESS.

A similar effect can be obtained by storing a new value into the register
`$pc', but not exactly the same.

     set $pc = 0x485

specifies the address at which execution will resume, but does not resume
execution.  That does not happen until you use the `cont' command or a
stepping command (*Note Stepping::).


File: gdb  Node: Signaling, Prev: Jumping, Up: Altering, Next: Returning

Giving the Program a Signal
===========================

`signal SIGNALNUM'     
     Resume execution where the program stopped, but give it immediately
     the signal number SIGNALNUM.
     
     Alternatively, if SIGNALNUM is zero, continue execution and give
     no signal.  This may be useful when the program has received a signal
     and the `cont' command would allow the program to see that
     signal.


File: gdb  Node: Returning, Prev: Signaling, Up: Altering

Returning from a Function
=========================

You can make any function call return immediately, using the `return'
command.

First select the stack frame that you wish to return from
(*Note Selection::).  Then type the `return' command.  If you wish to
specify the value to be returned, give that as an argument.

This pops the selected stack frame (and any other frames inside of it),
leaving its caller as the innermost remaining frame.  That frame becomes
selected.  The specified value is stored in the registers used for
returning values of functions.

The `return' command does not resume execution; it leaves the program
stopped in the state that would exist if the function had just returned.
Contrast this with the `finish' command (*Note Stepping::), which
resumes execution until the selected stack frame returns naturally.


File: gdb  Node: Sequences, Prev: Altering, Up: Top, Next: Concepts

Canned Sequences of Commands
****************************

GDB provides two ways to store sequences of commands for execution as a
unit: user-defined commands and command files.

* Menu:

* Define::         User-defined commands.
* Command Files::  Command files.
* Output::         Controlled output commands useful in
                   user-defined commands and command files.


File: gdb  Node: Define, Prev: Sequences, Up: Sequences, Next: Command Files

User-Defined Commands
=====================

A "user-defined command" is a sequence of GDB commands to which you
assign a new name as a command.  This is done with the `define'
command.

`define COMMANDNAME'     
     Define a command named COMMANDNAME.  If there is already a command
     by that name, you are asked to confirm that you want to redefine it.
     
     The definition of the command is made up of other GDB command lines,
     which are given following the `define' command.  The end of these
     commands is marked by a line containing `end'.
     
`document COMMANDNAME'     
     Give documentation to the user-defined command COMMANDNAME.  The
     command COMMANDNAME must already be defined.  This command reads
     lines of documentation just as `define' reads the lines of the
     command definition.  After the `document' command is finished,
     `help' on command COMMANDNAME will print the documentation
     you have specified.
     
     You may use the `document' command again to change the
     documentation of a command.  Redefining the command with `define'
     does not change the documentation.

User-defined commands do not take arguments.  When they are executed, the
commands of the definition are not printed.  An error in any command
stops execution of the user-defined command.

Commands that would ask for confirmation if used interactively proceed
without asking when used inside a user-defined command.  Many GDB commands
that normally print messages to say what they are doing omit the messages
when used in user-defined command.


File: gdb  Node: Command Files, Prev: Define, Up: Sequences, Next: Output

Command Files
=============

A command file for GDB is a file of lines that are GDB commands.  Comments
(lines starting with `#') may also be included.  An empty line in a
command file does nothing; it does not mean to repeat the last command, as
it would from the terminal.

When GDB starts, it automatically executes its "init files", command
files named `.gdbinit'.  GDB reads the init file (if any) in your home
directory and then the init file (if any) in the current working
directory.  (The init files are not executed if the `-nx' switch
is given.)  You can also request the execution of a command file with the
`source' command.

`source FILENAME'     
     Execute the command file FILENAME.

The lines in a command file are executed sequentially.  They are not
printed as they are executed.  An error in any command terminates execution
of the command file.

Commands that would ask for confirmation if used interactively proceed
without asking when used in a command file.  Many GDB commands that
normally print messages to say what they are doing omit the messages
when used in a command file.


File: gdb  Node: Output, Prev: Command Files, Up: Sequences

Commands for Controlled Output
==============================

During the execution of a command file or a user-defined command, the only
output that appears is what is explicitly printed by the commands of the
definition.  This section describes two commands useful for generating
exactly the output you want.

`echo TEXT'     
     Print TEXT.  Nonprinting characters can be included in
     TEXT using C escape sequences, such as `\n' to print a
     newline.  No newline will be printed unless you specify one.
     
     A backslash at the end of TEXT is ignored.  It is useful for
     outputting a string ending in spaces, since trailing spaces are
     trimmed from all arguments.  A backslash at the beginning preserves
     leading spaces in the same way, because `\ ' as an escape
     sequence stands for a space.  Thus, to print ` and foo = ', do
     
          echo \ and foo = \
     
`output EXPRESSION'     
     Print the value of EXPRESSION and nothing but that value: no
     newlines, no `$NN = '.  The value is not entered in the
     value history either.
     
`output/FMT EXPRESSION'     
     Print the value of EXPRESSION in format FMT.
     *Note Formats::, for more information.


File: gdb  Node: Commands, Prev: Sequences, Up: Top, Next: Concepts

Command Index
*************


* Menu:

* $_: Breakpoints.
* $_: List.
* $_: Memory.
* $__: Memory.
* break: Set Breaks.
* cd: Working Directory.
* clear: Clear Breaks.
* condition: Conditions.
* core-file: File Commands.
* define: Define.
* delete: Clear Breaks.
* directory: Source Path.
* disable: Disabling.
* display: Auto Display.
* document: Define.
* down: Selection.
* echo: Output.
* enable: Disabling.
* exec-file: File Commands.
* finish: Stepping.
* frame: Selection.
* handle: Signals.
* ignore: Conditions.
* info address: Symbols.
* info args: Frame Info.
* info break: Breakpoints.
* info convenience: Convenience Vars.
* info directories: Source Path.
* info display: Auto Display.
* info environment: Environment.
* info files: File Commands.
* info frame: Frame Info.
* info functions: Symbols.
* info history: Value History.
* info line: List.
* info locals: Frame Info.
* info registers: Registers.
* info signal: Signals.
* info sources: Symbols.
* info types: Symbols.
* info variables: Symbols.
* jump: Jumping.
* kill: File Commands.
* list: List.
* next: Stepping.
* nexti: Stepping.
* ni: Stepping.
* output: Output.
* print: Data.
* printsyms: Symbols.
* ptype: Symbols.
* pwd: Working Directory.
* quit: Input.
* return: Returning.
* run: Running.
* set-args: Arguments.
* set-environment: Environment.
* set-prompt: Input.
* set: Assignment.
* si: Stepping.
* signal: Signaling.
* silent: Break Commands.
* source: Command Files.
* step: Stepping.
* stepi: Stepping.
* symbol-file: File Commands.
* tbreak: Set Breaks.
* undisplay: Auto Display.
* unset-environment: Environment.
* up: Selection.
* whatis: Symbols.
* x: Memory.


File: gdb  Node: Concepts, Prev: Commands, Up: Top

Concept Index
*************


* Menu:

* $$: Value History.
* $: Value History.
* .gdbinit: Command Files.
* arguments (to your program): Arguments.
* artificial array: Arrays.
* assignment: Assignment.
* breakpoint commands: Break Commands.
* breakpoints: Breakpoints.
* call stack: Stack.
* clear breakpoint: Clear Breaks.
* command files: Command Files.
* conditions: Conditions.
* convenience variables: Convenience Vars.
* core dump file: Files.
* delete breakpoints: Clear Breaks.
* directories for source files: Source Path.
* disabled breakpoints: Disabling.
* enabled breakpoints: Disabling.
* environment (of your program): Environment.
* examining data: Data.
* examining memory: Memory.
* executable file: Files.
* exiting GDB: Input.
* expressions: Expressions.
* formatted output: Formats.
* frame number: Frames.
* frame pointer: Frames.
* frame: Frames.
* ignore count (of breakpoint): Conditions.
* init file: Command Files.
* initial frame: Frames.
* innermost frame: Frames.
* outermost frame: Frames.
* output formats: Formats.
* printing data: Data.
* registers: Registers.
* returning from a function: Returning.
* running: Running.
* selected frame: Frames.
* setting variables: Assignment.
* source path: Source Path.
* stepping: Stepping.
* symbol table: Files.
* user-defined commands: Define.
* value history: Value History.
* word: Memory.
* working directory (of your program): Working Directory.


Tag table:
Node: Top1038
Node: License2631
Node: Input9712
Node: Files11663
Node: File Arguments12120
Node: File Commands12825
Node: Switches15225
Node: Running17097
Node: Arguments18700
Node: Environment19436
Node: Working Directory21144
Node: Stopping21804
Node: Signals22567
Node: Breakpoints26013
Node: Set Breaks27715
Node: Clear Breaks30051
Node: Disabling31507
Node: Conditions33946
Node: Break Commands37149
Node: Error in Breakpoints40603
Node: Continuing41282
Node: Stepping42759
Node: Stack45128
Node: Frames46526
Node: Backtrace48411
Node: Selection49369
Node: Frame Info51330
Node: Source52919
Node: List53535
Node: Source Path57297
Node: Data59294
Node: Expressions60525
Node: Variables61771
Node: Arrays62566
Node: Formats63814
Node: Memory65443
Node: Auto Display70200
Node: Value History71813
Node: Convenience Vars73484
Node: Registers75665
Node: Symbols78568
Node: Altering81201
Node: Assignment81618
Node: Jumping82796
Node: Signaling84091
Node: Returning84584
Node: Sequences85489
Node: Define85941
Node: Command Files87605
Node: Output88790
Node: Commands90063
Node: Concepts91794

End tag table
